Method and apparatus for deodorizing liquids



- April 1951 H. R. RASMUSSEN 2,978,327

METHOD AND APPARATUS FOR DEODORIZING LIQUIDS Filed July 7, 1955 3 Sheets-Sheet 1 INVENTOR. t avg @oberi fiasmussen BY .8'M,M

ATT R IVEY6 April 1961 H. R. RASMUSSEN 2,978,327

METHOD AND APPARATUS FOR DEODORIZING LIQUIDS Filed July 7, 1955 S Sheets-Sheet 2 I N VEN TOR. %rrg Qaber .lPasm ussen BY 8M,Mi

ATTOR I EYS April 4, 1961 H s uss 2,978,327

METHOD AND APPARATUS FOR DEODORIZING LIQUIDS 3 Sheets-Sheet 5 Filed July '7, 1955 m R 3%. ms y mu. m

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United States Patent METHOD AND APPARATUS FOR DEODORIZING LIQUIDS Harry Robert Rasmussen, Enskede, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Filed July 7, 1955, Ser. No. 520,570

8 Claims. (Cl. 99-61) This invention relates to the deodorizing of liquids and more particularly to an improved method and apparatus for this purpose. 1

For deodorization of milk, cream, and other milk products, the method commonly used consists mainly of partial evaporization of theliquid as it is brought to boil, and leading oi? the steam formed during the boiling and which contains the odorous substances in the liquid. These substances are in the nature of gases dissolved in the liquid, which are more or less driven off together with steam during the boiling. To obtain as complete a deodorization as possible, it is necessary to drive off a comparatively large part of the water content, which involves a comparatively great consumption of heat. In some instances, the liquid has been treated in two stages by bringing it to boil in both stages, which also involves a high consumption of heat.

A large part of the gases constituting the odoriferous substances in liquids, such as milk or cream, maybe driven off from the liquid without boiling, by heating the liquid to a temperature which, though high, is nevertheless below the boiling point of the liquid at the absolute pressure existing in the deodorizing vessel. Utilizing this possibility in deodorizing of liquids of the kind referred to forms an element of the present invention.

According to the invention, a large part (if possible the main part) of the odorous gases to be removed is driven off in a first deodorization stage at a temperature below the boiling temperature corresponding to the absolute pressure existing in this first stage, whereupon the liquid is heated further and is brought to boil in a second stage. The two stages correspond to two vessels which preferably are under vacuum and operate at one andthe same absolute pressure. With thislarrangement, the temperature of the treated liquid in the first stage should be lower than the temperature in the second stage, for example,

ten degrees lower; and in the second stage the temperature corresponding to theabsolute pressure present is automatically obtained, since the liquid is led into the second stage from a pipe in which the pressure and temperature are higher than in the vessel of the second stage. Whenenter'ing the latterfthe liquid passes through a throttle of valve where boilingand a decrease in ternperature take place incident to the pressure drop.

By thus dividing the'deodorizing operation into two stages and driving off a large part of the odorous gases without boiling the liquid, aconsiderable saving in heat consumption is obtained. On the other hand, the deodorization is'efiected to such a high degree (in the sec- 0nd stage) that there is no reduction in the final deodoriza- In other words, a considerable reduction in the heat consumptionis obtained without any sacrifice in the degree of deodorization.

According to'one embodirnentof the invention, the steam driven off in the second stage is led through the vessel for the firststage. This steam isfled through only the upper portion of the latter vessel,; without coming into more intimate contact with the liquid flowing through in the deodorization process.-

heating section 12 in the plate apparatus.

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the vessel, this liquid, of course, having a lower temperature. The steam is preferably introduced tangentially into the first stage-vessel so that a cyclone effect is obtained, in which case this vessel is of cylindrical shape. Such an arrangement has the practical advantage that liquid which accompanies the steam from the second stage, and which may he of a considerable quantity, is separated in the first stage and there rejoins the liquid flow.

From the vessel of the first stage, the steam may be led through a heat exchanger where it is condensed as a result of preheating the liquid to be deodorized, so that the preheater forms a condenser for the steam. The 'remaining steam may be sucked ofi from the condenserpreheater by means of a vacuum pump.

A further characteristic of the invention, at least insome of its embodiments, is that all heat transmissions take place in a plate heat exchange apparatus of the type commonly used in dairies. ,Thus, the condenser for the steam driven oif in the second stage, and which also serves as a preheater, is constituted by a plate pack of such an apparatus. For recovering heat'from the heated liquid, the plate apparatus also comprises a regenerativesection where the liquid from the second stage is cooled by passage in counter-current heat-exchange relation to the preheated liquid passing to the first stage. The apparatus preferably comprises, in addition to this, a heating section for heating the liquid between the first and second stages, and a cooling section for final cooling of the treated liquid with water or other cooling medium.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which Fig. l is a schematic view of a preferred form of the new apparatus for carrying out the method of the invention, and

Figs. 2, 3 and 4 are front, top and side views, respectively, of the apparatus shown schematically in Fig. 1.

In the following it is assumed that the liquid to be deodorized is cream. The latter is delivered by a pump 1 (Fig. 1) through a feed pipe 2 to a preheating section 3 in the plate heat-exchange apparatus l. It is to he noted that the pump 1 is not shown in Figs. 2-4, because this pump is usually placed at some distance from the assembly shown in these figures. After the cream has passed through the section 3, it flows through the heating-side of a regenerative section 5', and further through a pipe 6 to a cylindrical vessel 7 corresponding to the first stage The cream entering the vessel 7 has a temperature of about 60 C. It passes down onto a sieving bottom 8 provided with a great number of holes through which the cream passes, so that it is divided into a large number of small parts (fine streams or drops). The latter then fall through the main part of the vessel 7 to its bottom. The vessel is evacuated to about 0.3 atm. absolute pressure. The drops falling through the liquid-free chamber of theyess-el'have a comparatively large area in relation to 'the liquid content, so that gases dissolved in the liquid depart easily and rapidlyand form steam which is sucked off'from the container, as will be described below. 'The stream or streams of cream may alternatively form 'thinsheets or films.

The cream discharges from the bottom of the vessel 7 through a pipe 9 to a pump 10 which increases the pressure on the cream and forces it through a pipe 11 to a The heating medium in section 12 is steam at about atmospheric pressure which is supplied through'a tube 31 and is discharged, in' the form of condensate, through a tube 32. In the section 12, the temperature of the cream is raised to C. At this temperature, and at atmosphericor higher pressure, the cream passes through a pipe 13 to a cylindrical vessel 14 which represents the second'stage in the deodorization process. Before or when entering the vessel 14, the cream passes through a throttle means 15 in the form of an adjustable valve or a stationary throttle washer, this throttle meanscausing the pressure on the cream to drop to the pressure existing in the vessel 7, or to about 0.3 atm. absolute pressure. Because of the pressure drop in the throttle means 15, the liquid temperature in the pipe 13 will be above the boiling point at the lower pressure existing in the vessel 14, and the liquid therefore is subjected to an intense boiling upon passing through the throttle means. The cream is led tangentially into the upper portion of the vessel 14 and will thus flow in a spiral path from the inlet to the outlet in the lower portion of the vessel. During this flow, a cyclonic effect is obtained which strongly promotes the separation of the steam bubbles from the cream. The steam formed in the vessel 14 is drawn off from this vessel in a manner which will be described below.

The cream, having now been freed to the desired degree from obnoxious smelling gases, passes from vessel 14 through a pipe 16 to a pump 17 which conveys it further through a pipe 18 to the cooling side of the aforementioned regenerative section 5. From there the cream passes through a pipe 19 to a cooler 20provided with a water supply line 33 and a water discharge line 34. After passing through the cooler 20, the cream leaves the plate apparatus at 21 at a suitable temperature, for example, 15 C. (When entering the apparatus through the pipe 2, the cream was at room temperature, that is, about 20 C.)

The second stage of the deodorization process, as previously mentioned, is carried out in the vessel 14. There is drawn off from the later a considerable amount of steam, together with those dissolved gases remaining in the cream from the first stage and which are to be removed from the cream. The steam and gases are sucked off from vessel 14'through a pipe 22 and pass first to the upper portion of the vessel 7 into which they are led tangentially, so that a cyclonic action occurs in this vessel, as well as in the second stage vessel 14. To the extent that the steam and gases entering through pipe 22 contain entrained liquid particles in the form of drops or large liquid bodies, the latter flow along a spiral path on the inner wall of the vessel 7 down to the bottom of the vessel, whereas the steam and gases leave the vessel 7 through a pipe 23 and pass to the plate section 3, which forms a condenser for this steam. The pipes 22 and 23 thus form a means for delivering steam from vessel 14 via vessel 7 to the cooling side of section 3. From the section 3, the remaining steam, together with the condensate formed, passes through a pipe 24 to a vacuum pump 25 constituting a means for maintaining subatmospheric pressure in the vessels 7 and 14. The vacuum pump may comprise a jet pump 26 combined with a centrifugal pump or other rotating pump 27 for circulating a water jet through the jet pump 26. The pipe 24, the condenser part of plate section 3, the pipe 23, the container 7, the pipe 22, and the container 14 are kept evacuated by the jet pump to 'a suitable pressure, that is, the above-mentioned absolute pressure of about 0.3 kg./cm.

The condenser section 3 (like the regenerative section 5, the heating section 12, and the final cooling section 20) consists of plate packs inserted between a frame 28 and a press-plate 29, as is customary in plate apparatus for dairy use.

I claim:

1. A method for deodorizing liquids, especially milk products, which comprises flowing the liquid continuously through a first stage and then through a second stage of treatment, both of said stages being maintained under substantially equal subatmospheric pressures, heating the liquid indirectly before passing it into said first stage, maintaining the temperature of the liquid in said first stage below the boiling point of the liquid at the absolute pressure existing in said first stage and below the liquid temperature in the second stage, indirectly heating the liquid passing from the first stage to the second stage, maintaining the temperature of the liquid in the second stage at about the boiling point of the liquid at the absolute pressure existing in the second stage, while admitting only said liquid into the second stage, and exhausting gases and steam by suction from the second stage to and through the first stage.

2. The method according to claim 1, in which the absolute pressure in said two stages is about 0.3 atm.

3. The method according to claim 1, in which the liquid, in its passage from the first to the second stage, is subjected to a pressure of at least atmospheric pressure and is heated to a temperature above said boiling point in the second stage.

4. The method according to claim 1, in which the liquid is led tangentially into the upper part of the second stage to create a cyclone effect therein.

5. The method according to claim 1, in which the liquid passing through said first stage is divided into a large number of small parts which are allowed to fall freely through part of said first stage, to release gases from the liquid.

6. The method according to claim 1, in which steam driven off from the liquid in the second stage is passed in heat exchange relation to the liquid flowing to said first stage.

7. The method according to claim 1, in which liquid from said second stage is cooled by passing it in heat exchange relation to the liquid flowing to said first stage.

8. The method according to claim 1, in which liquid from said second stage is cooled by passing it in heat exchange relation to the liquid flowing to said first stage, and in which steam driven off from the liquid in the second stage is also passed in heat exchange relation to the liquid flowing to said first stage.

References Cited in the file of this patent UNITED STATES PATENTS 1,693,034 Jensen Nov. 27, 1928 1,723,860 Hunziker Aug. 6, 1929 2,025,196 Cornell Dec. 24, 1935 2,077,227 De Bethune Apr. 13, 1937 2,084,894 Davis June 22, 1937 2,089,132 Murray Aug. 3, 1937 2,122,029 Davis June 28, 1938 2,207,928 McDonald July 16, 1940 2,516,099 Board et a1 July 25, 1950 2,631,105 Henszey Mar. 10, 1953 FOREIGN PATENTS 712,479 Great Britain -2. July 28, 1954 

1. A METHOD FOR DEODORIZING LIQUIDS, ESPECIALLY MILK PRODUCTS, WHICH COMPRISES FLOWING THE LIQUID CONTINUOUSLY THROUGH A FIRST STAGE AND THEN THROUGH A SECOND STAGE OF TREATMENT, BOTH OF SAID STAGES BEING MAINTAINED UNDER SUBSTANTIALLY EQUAL SUBATMOSPHERIC PRESSURES, HEATING THE LIQUID INDIRECTLY BEFORE PASSING IT INTO SAID FIRST STAGE, MAINTAINING THE TEMPERATURE OF THE LIQUID IN SAID FIRST STAGE BELOW THE BOILING POINT OF THE LIQUID AT THE ABSOLUTE PRESSURE EXISTING IN SAID FIRST STAGE AND BELOW THE LIQUID TEMPERATURE IN THE SECOND STAGE INDIRECTLY HEATING THE LIQUID PASSING FROM THE FIRST STAGE TO THE SECOND STAGE, MAINTAINING THE TEMPERATURE OF THE LIQUID IN THE SECOND STAGE AT ABOUT THE BOILING POINT OF THE LIQUID AT THE ABSOLUTE PRESSURE EXISTING IN THE SECOND STAGE, WHILE ADMITTING ONLY SAID LIQUID INTO THE SECOND STAGE, AND EXHAUSTING GASES AND STEAM BY SUCTION FROM THE SECOND STAGE TO AND THROUGH THE FIRST STAGE. 